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/***************************************************************************/
/* */
/* ftextend.h */
/* */
/* FreeType extensions implementation (specification). */
/* */
/* Copyright 1996-2001 by */
/* David Turner, Robert Wilhelm, and Werner Lemberg. */
/* */
/* This file is part of the FreeType project, and may only be used, */
/* modified, and distributed under the terms of the FreeType project */
/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
/* this file you indicate that you have read the license and */
/* understand and accept it fully. */
/* */
/***************************************************************************/
#ifndef __FTEXTEND_H__
#define __FTEXTEND_H__
#include <ft2build.h>
#include FT_INTERNAL_OBJECTS_H
FT_BEGIN_HEADER
/*************************************************************************/
/* */
/* The extensions don't need to be integrated at compile time into the */
/* engine, only at link time. */
/* */
/*************************************************************************/
/*************************************************************************/
/* */
/* <FuncType> */
/* FT_Extension_Initializer */
/* */
/* <Description> */
/* Each new face object can have several extensions associated with */
/* it at creation time. This function is used to initialize given */
/* extension data for a given face. */
/* */
/* <InOut> */
/* ext :: A typeless pointer to the extension data. */
/* */
/* face :: A handle to the source face object the extension is */
/* associated with. */
/* */
/* <Return> */
/* FreeType error code. 0 means success. */
/* */
/* <Note> */
/* In case of error, the initializer should not destroy the extension */
/* data, as the finalizer will get called later by the function's */
/* caller. */
/* */
typedef FT_Error
(*FT_Extension_Initializer)( void* ext,
FT_Face face );
/*************************************************************************/
/* */
/* <FuncType> */
/* FT_Extension_Finalizer */
/* */
/* <Description> */
/* Each new face object can have several extensions associated with */
/* it at creation time. This function is used to finalize given */
/* extension data for a given face; it occurs before the face object */
/* itself is finalized. */
/* */
/* <InOut> */
/* ext :: A typeless pointer to the extension data. */
/* */
/* face :: A handle to the source face object the extension is */
/* associated with. */
/* */
typedef void
(*FT_Extension_Finalizer)( void* ext,
FT_Face face );
/*************************************************************************/
/* */
/* <Struct> */
/* FT_Extension_Class */
/* */
/* <Description> */
/* A simple structure used to describe a given extension to the */
/* FreeType base layer. An FT_Extension_Class is used as a parameter */
/* for FT_Register_Extension(). */
/* */
/* <Fields> */
/* id :: The extension's ID. This is a normal C string that */
/* is used to uniquely reference the extension's */
/* interface. */
/* */
/* size :: The size in bytes of the extension data that must be */
/* associated with each face object. */
/* */
/* init :: A pointer to the extension data's initializer. */
/* */
/* finalize :: A pointer to the extension data's finalizer. */
/* */
/* interface :: This pointer can be anything, but should usually */
/* point to a table of function pointers which implement */
/* the extension's interface. */
/* */
/* offset :: This field is set and used within the base layer and */
/* should be set to 0 when registering an extension */
/* through FT_Register_Extension(). It contains an */
/* offset within the face's extension block for the */
/* current extension's data. */
/* */
typedef struct FT_Extension_Class_
{
const char* id;
FT_ULong size;
FT_Extension_Initializer init;
FT_Extension_Finalizer finalize;
void* interface;
FT_ULong offset;
} FT_Extension_Class;
/*************************************************************************/
/* */
/* <Function> */
/* FT_Register_Extension */
/* */
/* <Description> */
/* Registers a new extension. */
/* */
/* <InOut> */
/* driver :: A handle to the driver object. */
/* */
/* class :: A pointer to a class describing the extension. */
/* */
/* <Return> */
/* FreeType error code. 0 means success. */
/* */
FT_EXPORT( FT_Error )
FT_Register_Extension( FT_Driver driver,
FT_Extension_Class* clazz );
#ifdef FT_CONFIG_OPTION_EXTEND_ENGINE
/* Initialize the extension component */
FT_LOCAL FT_Error
FT_Init_Extensions( FT_Library library );
/* Finalize the extension component */
FT_LOCAL FT_Error
FT_Done_Extensions( FT_Library library );
/* Create an extension within a face object. Called by the */
/* face object constructor. */
FT_LOCAL FT_Error
FT_Create_Extensions( FT_Face face );
/* Destroy all extensions within a face object. Called by the */
/* face object destructor. */
FT_LOCAL FT_Error
FT_Destroy_Extensions( FT_Face face );
#endif
/*************************************************************************/
/* */
/* <Function> */
/* FT_Get_Extension */
/* */
/* <Description> */
/* Queries an extension block by an extension ID string. */
/* */
/* <Input> */
/* face :: A handle to the face object. */
/* extension_id :: An ID string identifying the extension. */
/* */
/* <Output> */
/* extension_interface :: A generic pointer, usually pointing to a */
/* table of functions implementing the */
/* extension interface. */
/* */
/* <Return> */
/* A generic pointer to the extension block. */
/* */
FT_EXPORT( void* )
FT_Get_Extension( FT_Face face,
const char* extension_id,
void** extension_interface );
FT_END_HEADER
#endif /* __FTEXTEND_H__ */
/* END */
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